Straight-Through and Cross-Over cables

Straight-Through Cabling

CAT 5 UTP cabling usually uses only four wires when sending and receiving information on the network. The four wires, which are used, are wires 1, 2, 3, and 6. When you configure the wire for the same pin at either end of the cable, this is known as a straight-through cable.

Straight-Through cabling

From the figure we can see that the wires 1 and 2 are used to transmit the data from the computer and 3 and 6 are used to receive data on the computer. The transmit wire on the computer matches with the receive wire on the hub. For the transmission of data to take place, the transmit pins on the computer should match with the receive pins on the hub and the transmit pins on the hub should match with receive pins on the computer. Here we can see that the pins 1, 2, 3 and 6 on the computer matches with pins 1, 2, 3 and 6 on the hub. Hence we use the term Straight-through.

Cross-Over Cabling

If we use want to connect two computers together with a straight-through cable, we can see that, the transmit pins will be connected to transmit pins and receive pins will be connected to receive pins. We will not be able to connect two computers or two hubs together using straight through cables.

Cross-Over Cabling

To connect two computers together without the use of a hub, we need a crossover cable by switching wires 1 and 2 with wires 3 and 6 at one end of the cable. If we shift the pins, we can make sure that the transmit pins on Computer A will match with the receive pins on Computer B and the transmit pins on Computer B will match with the receive pins on Computer A.

	Hub	Switch	Router	Workstation
Hub	Cross-over	Cross-over	Straight	Straight
Switch	Cross-over	Cross-over	Straight	Straight
Router	Straight	Straight	Cross-over	Cross-over
Workstation	Straight	Straight	Cross-over	Cross-over